Green Ethno-Materials Science: Sustainable Structural Materials from Amazonian Biological Resources
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tkhan20-kahn-sm-meche-2026-thesis.pdf
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13.33 MB
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83a2b7e38e502001222f9496d635586a
Author(s)
Khan, Talia M.
Advisor(s)
Buehler, Markus J.
Date Issued
February 2026
Publisher
Massachusetts Institute of Technology
Abstract
This thesis introduces ethno-materials science as a rigorous interdisciplinary framework for sustainable materials discovery that integrates traditional ecological knowledge with modern materials engineering. The central premise is that indigenous material practices refined through centuries of empirical use encode valuable information about structureproperty relationships that can systematically guide the identification, optimization, and ethical commercialization of high-performance bio-derived materials. Focusing on biological resources native to the Brazilian Amazon rainforest, this work experimentally characterizes and validates three exemplar material systems: curauá fibers (Ananas erectifolius) produced via tissue-culture micropropagation, munguba bark fibers (Pseudobombax munguba) for polymer reinforcement, and melanized fungal rhizomorphs from Marasmius yanomami as a source of bioderived melanin ("RhizoMel") for functional nanocomposites. Curauá fibers, traditionally employed by Indigenous Amazonian communities for basketry, ropes, and structural applications, were cultivated under controlled in vitro conditions to evaluate the influence of micropropagation on fiber performance and uniformity. The resulting fibers exhibited high cellulose content (77.2%), elevated crystallinity (73.5%), and tensile strengths exceeding 2.1 GPa, placing them among the strongest reported natural fibers. These properties surpass those of conventionally grown curauá and many widely used lignocellulosic reinforcements, demonstrating that biotechnological cultivation can enable scalable production of high-quality natural fibers while reducing land-use pressure on rainforest ecosystems. Complementary investigation of munguba bark fibers revealed an average cellulose content of 67.2%, exceeding that of commonly used jute fibers. When incorporated at 5 wt% into high-density polyethylene matrices, munguba fibers produced composites with tensile strengths up to 21.4 MPa and enhanced impact resistance reaching 12.0 kJ/m2 , depending on interfacial modification strategy. Scanning electron microscopy and Fourier-transform infrared spectroscopy confirmed favorable fiber morphology, surface roughness, and interfacial interactions, supporting efficient stress transfer and energy absorption within the composite system. In parallel, melanin extracted from melanized fungal rhizomorphs—naturally occurring mycelial structures with protective pigmentation—was systematically integrated into cellulose nanocrystal (CNC) films across controlled melanin concentrations and processing pH conditions. The resulting RhizoMel–CNC nanocomposites exhibited tunable broadband optical absorption, with transmittance varying from approximately 10% to 70%, pH-dependent dielectric permittivity spanning more than an order of magnitude (εr ≈ 5–58), and reproducible piezoelectric voltage responses under cyclic mechanical loading. These multifunctional properties arise from coupled CNC chiral ordering and melanin-mediated interfacial polarization mechanisms, indicating suitability for biodegradable sensing, energy-harvesting, and protective material applications. Through combined structural, mechanical, optical, and electrical characterization including XRD, FTIR, tensile testing, dielectric analysis, and electromechanical measurements, this thesis quantitatively demonstrates how indigenous material selection aligns with highperformance biological architectures. Beyond material validation, the work proposes an ethical model for scientific co-creation with indigenous communities that emphasizes benefit-sharing, territorial protection, and conservation-aligned value chains. By coupling renewable Amazonian biological resources with scalable processing strategies such as tissue-culture propagation and solution-based composite assembly, ethno-materials science is established as a replicable methodology for translating long-standing material practices into contemporary engineering systems that support technological innovation, sustainable manufacturing, and forest preservation.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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